Centrifugal fan



original Filed ct. e, 1920 2 sheet.; 51111111 1 attoamcg Mar. 6, 1923.

' '.J. A. WATKINS GENTRIFUGALv FAN 'original Filed oct. e, 1920 2 sheets-sheet 2 SM2-Moz.-

g QM-2 M24/22%.

, 'atkomufs IIIIIIIIIH Patented Mar.I 6, 1923.

UNIT sr AENT OFFICE.-

J'AMES A. WATKINS, OF DETROIT, MICHIGAN, ASSIGNOR '1"0` AMERICAN BLOWER COMPANY, OF DETROIT, MICHIGAN, A `COBPORAIION OF MICHIGAN.

CENTRIFUGAL FAN.v

Application led October 6, 1920, Serial No. 414,987. Renewed November 20, 1922*.

To a-ZZ 'whom t may concern.'

Be it known that I, J AMES A. WATKINS, a

citizen of the United States, residing at Detroit, in the county of Wayne and btate of Michigan, have invented certain new and useful Improvements in Centrifugal Fans, of which the following is a specification, reference being had therein to the accompanying drawing. v

This invention relates to improvements in centrifugal fans and has for its object to provide an improved method of discharging air from the wheel into the atmosphere, and to simplify and increase the efficiency of such devices; to provide an improved centrifugal fan having an eflicient peripheral discharge extending all around the same, the necessity for the scroll volute auxiliary housing customarily employed with centrifugal fans to enclose the same and directthe air ow, being entirely avoided. v

Experience has shown in discharging air from the ordinary multi-blade centrifugal i fan, the air does not have a suiicient velocity when it leaves the wheel, to force it away from the wheel far enough to allow it to diffuse without agitation, that is, the air starts to diffuse immediately upon leaving the wheel, so that the strata of air around the wheel is comparatively dense and the succeeding particles are hindered in leaving the wheel, thereby causing considerable agitation.

When the air is given sufficient directive velocity the diffusion takes place a considerable distance from the wheel so that less disturbance is caused at the exit of the blades and consequently a more efiicient wheel is obtained. This result is obtained b the present invention, an important novel c aracteristic of the invention residing in the provision of an outer annular converging nozzle part constructed and arranged to form a substantial continuation of the.

shrouding ofthe wheel and to conform to the path of the air, asl it wouldleave the wheel under open discharge conditions, said annular nozzle part effecting no material change in the direction of the air, but acting to simply continue the convergence to such a point as to give it sulicient directive velocity, and at this point to eii'ectively discharge the same. y

The invention, with other objects and ad vantages thereof, and the particular construction, combinations and arrangements of parts comprising the same, will be understood from the hereinafter contained detailed description when considered in connection with the accompanying drawings forming part hereof, and wherein is illustrated several embodiments-of the invention.

In the drawings Figure 1 is a vertical central section of a centrifugal fan constructed in accordance with the present invention.

` Figure 2 is a front elevation of one-half of the wheel illustrated in Fig. 1, with a part of one end plate broken away and the blade shown in section.

Figure 3 is a vertical central section of a modification of the construction shown in Figs. 1 and 2.

, Figure 4 is a vertical central section illustrating the application of the invention to a different typeof fan wheel.

Figure 5 is a front elevation, with parts in section, of the construction illustrated in Fig. '4.

Figure 6 is a side elevation with parts in section illustrating a different form of mounting and use of the fan construction illustrated in Figs. 1 and 2.

Figures 7 and 8 are detail views of the blades.

wha@ r have illustrated in the drawingsconstructions in which only two different types of fan wheel 'are employed, it will ofcourse be understood that the invention is applicable to the various other types of fan wheels, that variations and changes in the particular constructions illustrated, and the carrying out of the invention in other forms, as will appeal to those skilled in the art and falling within the scope of the appended claims, may be practiced without departing from the principles of the invention.

In Figs. 1 and 2 of the drawings, a fan wheel structure is shown of the kind dediameter than the eye a. The blades g are secured in any suitable manner to the disk f r and the cone disk it. In the present instance the blades are 4shown provided with tenons r integral projecting portions g entering recesses provided in the disk f and disk h. In the particular construction shown the blades are sixteen in number, although the number of blades may be varied according to the size of the fan. The inner part c o-f each blade is radial, or closely lapproximates to a plane radiating from the axis. The blade is then curved in preferably a segment of a cylinder,

tion of the arrow z' in Fig. 2; hence, the

blades are curved .forwardly so that their outer or discharging end portions occupy planes tangential to a circle smaller than the circumference of the wheel.

While, as will be understood, theproportions for the wheel may be varied to meet different conditions, proportionsthat have been found to be especially satisfactory are as follows, being stated with relation to the radius of the fan wheel as unity:

r1`he axial width of the blade at its inner ,or inlet side is .57, and at its outer or discharge side is from .40 to .50; the radial dimension of the blade is ..32 lat the front or inlet side and .50 at the rear or disk side.

The radial portion /v of the blade has an extreme length of .22; the portion has a length of .0625; the radius of the curved portion lw is .25. A feature of great importance is the angle y which should closely approximate 60 degrees. rI`he distance from the tip of one blade to the back of the next preceding one (measured on the line j, u, Fig. 2) should approximate the space between the blades at their inner front edges.

In accordance with the teachings of the present invention, an annular peripheral discharge nozzle is provided, the volute scroll housing` customarily employed being eliminated. In the particular embodiment of the invention illustrated in Figs. 1 and 2, the annular nozzle 1 is constructed as a part of the fan wheel for rotation therewith. Said nozzle is formed by annular extensions of the wheel shrouding or the outer portions of the disks f, it, the extensions having converging wall portions and outer marginal diver-ging lip portions providing a somewhat restricted intermediate nozzle portion with an enlarged outlet portion. The annular extensions of the disk f have an inner portion 2 extending at an inward inclination, and an adjoining part 3 extendin at an outward inclination at an angle aient equal to the angle, of inclination of the part 2. The extension 4 of the coned disk 7L is shown extending at the same angle ,as the angle of the coned face of the conical disk. 5, 6 designate the marginal lip portions, the lip portions being shown flaring outwardly on a slight curve.

rlhe nozzle 1, which constitutes a substantial continuation of the shrouding of the wheel, is shaped to conform to the path of the air as it would leave the wheel under open discharge conditions. In this way no material change in the direction of the air is effected, the nozzle simply acting to continue the convergence of the air to such a point as to give it suiicient ldirective ve locity, and at this point providing an efticient discharge of air.

The invention in its broader aspect comprehends such modified constructions as indicated in a general way in Fig. 3 of the drawings, in which the annular peripheral nozzle part is constructed as a separate part from the fan wheel and is stationary with reference thereto. In this structure 7 designates the fan wheel and 8 the annular nozzle, the latter, in this instance, being mounted on any suitable forrno'f support (not shown).

In Figs. 4 and 5 of the drawings the invention is shown applied toI a multi-blade type of wheel, the wheel being shown as comprising a hub 9,- end plates 10, 11 and blades pr fans 12. -13 designates the annular peripheral nozzle formed by extensions of the shrouding or outer portions of the end plates 10, 11. rIhe nozzle part has inwardly converging' wall lportions, and outwardly Haring marginal lips. In this instance, the walls 14, .15 of the extensions both extend inwardly from the wheel shrouding to the marginal lip portions 16 and 17, the Wall 14 extending at a greater angle than the wall 15.

It )gill be noted that the constructions hereinbefore described are such as to provide an efficient peripheral discharge, Athe necessity for the usual auxiliary housing being entirely avoided and a more simple advantageous centrifugal fan ystructure afforded. Those forms of the device in which the annular nozzle part rotates with the fan wheel also possess the advantage that the` skin friction through the fan is materially reduced, thereby reducing the skin velocity of the air under pressure. Fans constructed in accordance with the present invention are adapted for general purposes, but have been found especially valuable for gas engine cooling. My improved fan is also particularly advantageous for use as a desk fan for oilices, and for dining lroom tables, being more ehcient than the ordinary four-blade being mounted on avertical shaft 22. 23

designates a suitable' motor.

What I claim is:

. l. A centrifugal fan consisting of an unenclosed fan wheel provided with an open annular peripheral discharge nozzle extending beyond the delivery end portions of the blades and rotatable with the fan wheel.

2. A centrifugal -fan consisting of an unenclosed fan wheel provided with an open annular peripheral discharge nozzle rotatable with the fan. wheel,I said discharge nozzle extending beyond the delivery end portions of the blades and having opposing annular outwardly converging walls.

3. A centrifugal fan consisting of a fan wheel provided with an open annular peripheral discharge nozzle rotatable with the fan wheel, said discharge nozzle having an annular constricted portion with an adjoining enlarged outlet portion. l

4, A centrifugal fan consisting of a fan wheel provided with an open annular peripheral discharge nozzle rotatable with the fan wheel, said nozzle having opposing annular outwardly converging walls, and adjoining outwardly diverging wall portions.

5. A centrifugal fan consisting of an unenclosed fan wheel provided with an open annular peripheral discharge nozzle rotatable with the fan wheel, said discharge nozzle being formed by oppositely disposed annular plate lportions extending beyond the outer ends of the blades of the wheel.

6. A centrifugal fan including a fan wheel comprising a flat back-disk section disposed at right angles to the axis of the wheel, a front coned ring, blades between the disk and ring, said back-diskv section and coned ring having opposing outer peripheral extensions forming an annular nozzle part. y

7. A centrifugal fan including a fan wheel comprising a flat back-disk section disposed at right angles to the axis ofthe wheel, a front coned ring, blades between the disk and ring. said back-disk section and coned ring having Opposing outer peripheral extensions forming ,an 4annular nozzle part, said back-disk section having an inner annular portion extending at an inward inclination, and an outer portion extending at an outward inclination. l,

8. A centrifugal fan including a fan wheel comprising a flat back-disk section disposed at right angles to the axis of the wheel, a front coned ring, blades between the disk and ring, the back disk section and'coned ring having opposing outer peripheral extensions lforming an annular nozzle part, the back disk extension having an inner annular portion extending atan inward inclination and anouter portion extending at an outward inclination, andthe said extension of the coned ring extending at an inward inclination at the angle of the coned V ring.

9. A centrifugal fan including a fan wheel vc omprising a flat back-disk section disposed '-at right angles to the axis of the wheel, a

front coned ring, blades. between the disk and ring, said back-disk section and coned ring havlng opposing outer peripheralextensions forming an annular nozzle part, with an enlarged'annular outlet part.'

10. A centrifugal fan including la fan wheel .comprising a flat back-disk section disposed at right angles to the axis of the wheel, a front coned ring, said back disk section andconed ring having opposing outer pe-' ripheral extensionsl forming an annular nozzle part, said back-disk extension having an inner annular portion extending at an inward inclination, and the said extension of the coned ring extending at an inwardinclinat'ion at the angle of the coned ring, and the coned ring and back-disk section having outer annular diverging outlet portions.

11. centrifugal fan wheel consisting of a back disk and front ring withblades arranged therebetween, the inner portions of said blades occupying radial planes for a distance of approximately one-fifth the radius of the wheel, the outer or tip portions occupying oblique planes for a distance approximately one-sixteenth the radial dimension of the wheel, said planes being approximately sixty degrees from said radial planes, and the intermediate portions of the blades curved in approximately the segment of the cylinder having a. radius about one-half the radius of the fan wheel, said back disk and front ring having opposing outer peripheral integral extensions forming an annular nozzle part. f

'12. A centrifugal fan wheel consisting of a back disk, a front coned ring, and blades therebetween, the radial vdimension of the blades at said disk approximating one-half .the radius of the wheel and at said ring apaxial dimension being from four to live tenths the radial dimension of the Wheel, the inner` portions of theblades occupying radial planes, and the 'blades being then curved forwardly, and terminating in oblique tip portions, said back disk and front coned ring having peripheral integral extensions forming a constricted annular nozzle part.

13. A centrifugal fan wheel consisting of a back disk and front ring, and blades arranged therebetween, the blades at their inner portions approximating to radial planes, their outer or tip portions occupying oblique planes for a distance approximating onetenth the radial dimension of the wheel, and

' their intermediate portions curved in approximately the segment of a cylinder, said back disk and front ring having opposingA outer peripheral integral extensions forming an annular nozzle part.

14. A centrifugal fan consisting of an unenclosed fan wheel having end plates and blades therebetween and provided with an open annular peripheral discharge nozzle formed by integral annular extensions of the end plates beyond the outer ends of the blades.

ln testimony whereof l hereunto aiiix my signature in the presence of two witnesses. 30

J AMES A. WATKINS. Witnesses:

F. R. STILL, y EDWIN BREDE. 

